I was trying to replace a few electrical outlets around the house with new tamper-resistant ones. When I pulled one of the outlets out of the box, I noticed that 1) there was no ground wire anywhere, 2) two white wires were under the same screw and one single black wire on the other side. This was a non-GFCI outlet in the kitchen.
I tried another outlet in the living room and in this case there were two hot wires under the same screw and two white wires under another screw on the other side of the outlet. Before I turned off the power, I had tested both outlets with a receptacle tester that showed they were correctly wired.
Is there a reason why these wires were connected to the same terminal? Should I replicate the same arrangement when installing the new outlets? Or should I put these wires under different screws?